Not applicable.
This invention relates to radar systems and more particularly to high performance, compact, portable radar systems which are field programmable for use in a variety of different applications.
As is known in the art, there is an increasing trend to include radar systems in commercially available products. For example, it is desirable to include radar systems in automobiles, trucks boats, airplanes and other vehicles. Such radar systems must be compact and relatively low cost.
Furthermore, some applications have relatively difficult design parameters including restrictions on the physical size of the structure in addition to minimum operational performance requirements. Such competing design requirements (e.g. low cost, small size, high performance parameters) make the design of such radar systems relatively challenging.
In automotive radar systems, for example, cost and size considerations are of considerable importance. Furthermore, in order to meet the performance requirements of automotive radar applications, (e.g. coverage area) a relatively sophisticated array antenna and radar and transmit circuitry is required.
It would, therefore, be desirable to provide a radar system having relatively high performance characteristics and which is compact, portable and relatively low cost.
The present invention provides a millimeter wave (MMW) radar system on a single low temperature ceramic substrate provided from a plurality of Low Temperature Co-fired Ceramic (LTCC) circuit layers. The single LTCC substrate has a top antenna cover or radome layer disposed over an antenna element or radiator layer. The cover or radome layer is used to tune the radiating elements on subsequent radiator layers. MMW transmitter and receiver circuit components are disposed on a second or bottom surface of the single LTCC substrate. Transmitter and receiver circuitry is integrated within the layers of the LTCC substrate to couple the antenna to the transmitter and receiver components. In one embodiment, the antenna is provided from an array of radiating antenna elements embedded in the LTCC substrate with array feed and beamforming circuitry embedded and integrated throughout the different layers of the LTCC substrate. Transmitter circuit components including but not limited to a voltage controlled oscillator (VCO) and a power amplifier as well as receiver circuit components including but not limited to a low noise amplifier (LNA), a mixer and a video amplifier are disposed on the bottom surface of the LTCC substrate. The transmitter and receiver circuit components are coupled to transmit and receive antennas as well as other transmit and receive circuitry through via connections provided in the LTCC substrate. In this manner, a highly integrated, single substrate MMW radar system is provided.
Digital signal processing (DSP), power circuits, control circuits and interface circuits are disposed on a printed wiring board (PWB) which can be coupled to the MMW radar system disposed on the LTCC substrate via a flex cable.
In one embodiment, the LTCC substrate comprising the antenna and MMW transmit and receive circuits is disposed in a housing. The LTCC substrate is disposed in the housing over a first support structure which spaces the antenna aperture a predetermined distance from a first or internal surface of the housing. Also disposed in the housing over a second support structure is the PWB. The second structure spaces a surface of the PWB a predetermined distance from the second surface of the LTCC substrate. Thus, the LTCC substrate and the PWB are disposed in a single common housing. In one embodiment, a flex circuit couples the circuit components disposed on the LTCC substrate to the circuit components disposed on the PWB. Thus the radar is provided as an integrated structure having a relatively connector-less interface. The housing is provided having a single connector through which RF, DC and logic signals are provided. Furthermore, an EMI shield is disposed in the housing to reduce the amount of radiation emitted through the housing from locations other than the antenna aperture. While the integrated single substrate MMW radar of the present invention is particularly well-suited for automotive radar systems, especially active electronically scanned antenna automotive radar systems, it is understood that the radar may also be used in other radar system applications.